“We have quite a few wells up there,” said Roy Coox, the general manager of the water district. “We own a large part of that valley, and under that valley is the largest groundwater basin in San Diego County. It’s a matter of getting it out. We pump water from the wells, which then goes into ditches, which then goes into the lake.”

Coox would prefer that the lake be filled with rainwater, because it can cost the district about $100,000 a month in electricity to run the pumps.

“That was the original intention, and that’s why the dam was built,” Coox said. “But what’s been happening lately, whether it’s climate change or whatever, we’ve had some very dry years over the last decade, to a point where the lake would have dried up if not for the fact we could pump well water into it.”

At one time, Lake Henshaw held far more water than it can now.

In the early 1980s, a seismic study was done showing that the earthen dam, which sits atop an earthquake fault, would be unable to withstand a big quake. The result was that a backup rock-filled dam was built behind the first one and the water level was taken down significantly.

Once, more than 200,000 acre-feet of water could be stored in Henshaw. One acre-foot equals 325,851 gallons. Today it’s about 5,000 acre-feet, a number that could grow in the spring, should the rains come, to 10,000 or 15,000, Smith said.

During any one month, the dam can release about 3,000 acre-feet of water into the canals.

Perhaps the single best view, the best way to see as much of the property as possible at once, is from a Cleveland National Forest lookout a short ways up East Grade Road off state Route 76 just west of the lake.

The district employs three people who live with their families in homes next to the dam. Much of their time is spent maintaining and repairing the wells.

The beauty, many would say, is that it is unlikely the property will ever be developed.

Over the years, the district has entertained proposals for various projects, but building houses there would require water.

“Development is something we have tried to prevent,” Coox said. “No. 1, it would compete for the water supply. We want as much water getting into the lake and then coming down to our ratepayers rather than having it used up there.”

Development would also bring water-quality issues.

“If you have houses, you have runoff, stormwater, sewage,” Coox said. “What do you do with all that? It could impact the water supply.”

Development would be forbidden under an agreement reached, after lengthy litigation, with a number of local Indian tribes over water rights. The lawsuit has been settled but is still awaiting federal approval.

“Our board of directors has always historically said we have no interest in developing because our primary purpose is to keep all that land available for water,” Coox said.

“It’s terrific that the irrigation district is protecting the land and has done so more than 50 years,” said John Randall, associate science director for the Nature Conservancy in California.

“It yields pure, fresh water and has the co-benefit, from our perspective, of protecting a big wildlife habitat.”